Internal combustion engine manufacturers are constantly seeking to improve the longevity and reliability of their engines. One method of improving an engine's longevity is to include oil control rings on the pistons of the internal combustion engine. Oil control rings perform the dual functions of minimizing oil consumption while simultaneously ensuring sufficient lubrication between the piston and the cylinder wall. Oil control rings are commonly designed to form a compromise between these two functions. In order to minimize oil consumption, the oil control rings ideally scrape off as much oil as possible from the cylinder wall during the down-stroke of the piston in the direction of the oil chamber. In order to ensure sufficient lubrication to minimize friction and wear, the oil control rings ideally maintain a minimal oil film between the oil control ring and the cylinder wall.
Oil control ring design must maintain the compromise between reducing oil consumption and maintaining sufficient lubrication over the life of the engine. The lifespan of an internal combustion engine may encompass years of operation. Excessive wear on the oil control ring outer radial surface may widen the gap between the oil control ring and the cylinder wall. This excessive wear can have a negative impact on the oil consumption of the engine. It is therefore, highly desirable to minimize the amount of wear the oil control ring experiences during its operational lifespan.
Oil control ring designs may utilize expander spring elements to bias ring surfaces into contact with the cylinder liner surface. The amount of force exerted on the cylinder wall may also play a role in controlling the oil film thickness. Oil control rings with larger surface areas of contact typically are effective at resisting radial wear, but may also require an undesirably large or rigid expander spring element to generate adequate biasing force. An expander spring element with a large spring rate may make installation of the oil control ring assembly difficult during assembly.
Accordingly, there is a need for an oil control ring assembly that provides an improved balance between reducing oil consumption and sufficient lubrication. There is further a need for an oil control ring that reduces wear and allows for the use of expander spring elements with reduced spring rates.